This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. Primary support for the subproject and the subproject's principal investigator may have been provided by other sources, including other NIH sources. The Total Cost listed for the subproject likely represents the estimated amount of Center infrastructure utilized by the subproject, not direct funding provided by the NCRR grant to the subproject or subproject staff. Multiple Reaction Monitoring (MRM) is a method of choice for accurate quantitation of low-abundance proteins in a complex background. MRM analysis of low abundance proteins is, however, sensitive to interference from other components in the sample that have the same precursor and fragment masses as the monitored transitions. Care is usually taken to avoid such interferences during development of MRM assays, however, unanticipated interference may still appear when the finished assay is applied to real samples. We used computer simulations as a tool to investigate the feasibility of correction for interference in MRM analyses.